I. Field of the Invention
This invention relates generally to portable, on-site metal machining equipment, and more particularly to an apparatus that can be mounted on a piping component for machining a surface of that component.
II. Discussion of the Prior Art
Oil refineries, chemical processing plants, pipeline companies and power plants typically provide fluid handling through piping systems where adjacent piping components are connected together by running bolts through mating flanges thereof. Such piping components may include straight pipe sections, elbows, nozzles, reducers, valves, etc. These components are typically subjected to fluids under high pressure, high temperatures, adverse atmospheric conditions, and having corrosive properties. Over time, such piping components may develop leaks due to scoring, warpage, and metal erosion, especially on flange faces. When this happens, it is necessary to machine the flange faces to remove grooves due to scoring and to restore a true flat surface to the flange meeting the original specifications for the pipe segments. Flanges on large diameter pipes also will include an annular groove having tapered side walls for receiving a metal seal ring therein. These grooves are also subject to wear and periodically need to be machined to insure seal integrity. Flanged pipes may also require internal diameter boring and outside diameter turning operations in the filed.
When it is considered that in many industrial installations, the piping components may vary anywhere from about 30 inches to 120 inches in diameter and may weigh several tons, it is impractical to transport such pipe components to a machine shop facility for refurbishment. Accordingly, a need exists for a machine for refacing flanges of piping components in the field.
In the Hunt Patent, U.S. Pat. No. 4,852,435, there is disclosed a portable machining tool for refacing or regrooving pipe flanges. It comprises a chuck that is adapted to be mounted within the bore of the pipe component to be refurbished. The chuck supports a machine body that is motor driven so as to rotate about an axis that is aligned with the center of the chuck. Mounted on the machine body is a tool bar that is fed in a direction transverse to the longitudinal axis of the pipe in which the chuck is mounted and it carries a cutting tool for engaging the surface of the flange being refaced so as to remove metal as the tool bar is being fed across the face of the flange.
Another portable flange facer adapted for use in the field is available from the Climax Machine Tool Company of Newberg, Oreg., and which is more particularly described in the Strait Patent, U.S. Pat. No. 5,630,346. With reference to that patent, its tool bar 200 feeds radially in and out. This presents a problem when working in confined spaces. More importantly, the feed system depicted in FIGS. 4, 5 and 6 of the '346 patent does not provide continuous feed. Instead, the feed stops and starts with each actuation of the cams 100A and 100B on the rocker arms 152A and 152B. This tends to leave an uneven surface finish. Such a condition is not acceptable in certain flange sealing applications.
The prior art devices suffer from a number of other drawbacks that limit its capabilities. For example, in the Strait '346 patent, the tool base 234 cannot swivel and, hence, the cutting tool 254 cannot be used for cutting angled grooves when desired.
It is sometimes advantageous to mount the chuck to the inside diameter of the pipe component whose flange is to be refaced. In other applications, it is advantageous to affix the chuck to the perimeter of the flange itself. No provision is made in the prior art for allowing one or the other of these two mounting modes. The device described in the Hunt '435 patent suffers from a number of operational deficiencies. First of all, there are no mitering capabilities in the chuck assembly, making setup and centering somewhat difficult. Moreover, there is no provision for translating the rotatable main body 70 relative to the spindle 10. In terms of performance, the feed resulting from the use of the feed cam 94 on the cam follower 96 results in an inferior surface finish due to the inherent lurching involved. Further, there is no provision in the Hunt machine for adjustment of the rotational bearing 72 following a period of use and resulting wear. Furthermore, it is not possible to reverse the feed direction without first removing and reversing the position of the feed slave unit 110.
It is, therefore, desirable to have an end prep facer for refurbishing piping components that obviates the aforementioned problems inherent in prior art machines used for this purpose.